Article pick-up and transfer apparatus

ABSTRACT

An article handling apparatus including a vertically reciprocable carriage provided with magnetic means for removing a single article from a stack of articles and delivering such article to an overhead conveyor which advances such article in a path normal to the path of movement of the carriage to a discharge station for removal from the conveyor upon demand.

BACKGROUND OF THE INVENTION

This invention relates generally to the article handling art and, moreparticularly, to an article pick-up and transfer assembly for deliveringarticles one at a time to an article feed conveyor.

Various machines have been devised for removing a single article from agroup or stack of articles and delivering such articles one at a time toan automated feed conveyor so as to avoid the tedious and monotonouschore of manually placing articles on the feed conveyor as space is madeavailable thereon. For example, in an automated baking operation,machines have been developed for removing a single baking pan or trayfrom a stack of trays and delivering such tray to an automatic trayfeeding conveyor leading to a tray filling station. While such knownmachines have eliminated the labor forces otherwise required formanually feeding trays onto the automated conveyor system, they have notbeen entirely satisfactory. For example, these known devices employ aplurality of mechanical fingers engagable beneath the tray for liftingsuch trays one at a time from the stack. However, should one or morefingers become slightly misaligned, as often occurs during usage, orsomewhat worn, they cannot perform their intended function properly andoften pick up more than one tray or drop a tray while in transit. This,of course, interrupts not only the tray pick-up and transfer operationbut also the subsequent operations of the automated tray feedingconveyor and operations downstream of the tray feeding conveyor.

SUMMARY OF THE INVENTION

The article pick-up and transfer assembly of the present invention, ashereinafter described, avoids the above problems by providing a simple,rugged and durable article pick-up and transfer assembly of generalutility for efficiently and positively lifting a single article from astack of articles and automatically delivering such single article to anoutput station upon demand.

The article pick-up and transfer assembly of this invention ischaracterized by the provision of a pair of vertically reciprocablecarriages movable in unison, each having a plurality of substantiallyuniversally suspended magnets adapted to orient themselves for firmengagement with portions of variously configurated articles for removingand lifting a single article from a stack of such articles upon movementof the carriages away from the stack. The article is lifted onto anoverhead conveyor belt and held thereto by magnetic forces for deliveryto a discharge station. A stripper, responsive to the demand for anarticle, is operative to strip the article from the conveyor belt ontoan output station.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of an article pick-up and transferassembly, constructed in accordance with this invention;

FIG. 2 is a top plan view of the apparatus of FIG. 1;

FIG. 3 is a vertical sectional view, taken about on line 3--3 of FIG. 1;

FIG. 4 is a fragmentary rear elevational view, illustrating a portion ofthe tray conveyor frame;

FIG. 5 is a fragmentary side elevational view, looking in the directionof arrows 5--5 in FIG. 3;

FIG. 6 is a top plan view of a carriage forming a part of the presentinvention;

FIG. 7 is a vertical sectional view, taken about on line 7--7 of FIG. 6;

FIG. 8 is a rear elevational view of the carriage of FIG. 6;

FIG. 9 is a diagrammatic view of the path of travel of an articlehandled by the pick-up and transfer apparatus of this invention;

FIG. 10 is a schematic illustration of the pneumatic system incorporatedin the apparatus of this invention; and

FIG. 11 is a diagrammatic illustration of an electrical control circuitfor use with the apparatus of this invention.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

Referring now to the illustrative embodiment depicted in theaccompanying drawings, there is shown in FIG. 1 an article pick-up andtransfer assembly, generally designated 20, constructed in accordancewith this invention. While the invention is in no way limited thereto,the article pick-up and transfer assembly 20 is especially adapted topick up a single tray from a stack and transfer such tray to a desiredstation. In the illustrative embodiment, assembly 20 transfers the trayto a position overlying a tray feed conveying arrangement 21 so that thetray may be deposited on conveyor 21 when space is available thereon toreceive the same. Transfer assembly 20 and conveyor 21 are incorporatedin an automated bakery operation in which empty trays are fed alongconveyor 21 to a tray filling station (not shown) wherein discreteportions of a dough mixture are deposited on the tray for ultimateconveyance to an oven to form rolls, buns, or other baking products.

Pick-up and transfer assembly 20 includes a base 22 suitably supportedon a floor surface and an upstanding frame 23 rigidly secured to base22. A pair of laterally spaced endless conveyor belts 25 are trainedabout a drive pulley 26 and an idler pulley 27 suitably journalled on asupport 28 rigidly secured to base 22. Drive pulley 26 is rigidlymounted on a rotatable shaft 29 (FIG. 1) having a pulley 30 affixedthereto and about which a drive belt 31 is trained. Belt 31 also isguided about a drive pulley 32 rigidly secured to an output shaft 33operatively connected to a drive motor M2 through a suitable gearreduction mechanism 35. Thus, motor M2 is effective to drive conveyorbelts 25 in unison in a counterclockwise, endless orbital path to move astack of trays 36 leftwardly, as viewed in FIG. 1, to a tray-pick upstation 37.

Pick-up and transfer assembly 20 includes means for removing trays 36one at a time from a stack of trays at pick-up station 37 and verticallyraising such trays for presentation to a tray transfer conveyor,generally designated 38, for a purpose to be explained. Such meansinclude a pair of laterally spaced, opposed carriages 40 (FIG. 3)vertically reciprocable together in synchronization on verticallyextending, paired support rods 41 mounted at their opposite ends onframe 23. Both carriages 40 are identical in construction and operativein a similar manner, but oriented in an opposed relation. Accordingly,it is believed that a detailed description of only one carriage 40 willsuffice, it being understood that the same reference characters will beapplied to similar parts.

As best shown in FIGS. 6, 7 and 8, each carriage 40 comprises a pair oflaterally spaced, upright plates 42 and 43 connected together by a crossplate 45 extending transversely therebetween. A pair of verticallyspaced bearing blocks 45 and 47 are welded or otherwise fixedly securedto the rear side of cross plate 45 adjacent each opposite end thereof atthe juncture of cross plate 45 with plates 42 and 43. These bearingblocks 46 and 47 are suitably bored for sliding movement on support rods41. A pair of plates 48 and 50 are welded or otherwise fixedly securedto the inner faces of plates 42 and 43 adjacent the lower ends thereofand extend substantially lengthwise thereof. A plurality of links 51 arepivotally mounted at their upper ends to the outer faces of plates 42,43, 48 and 50 by pins 52 projecting laterally outwardly therefrom. Aplurality of permanent bar magnets 53 are pivotally mounted on the lowerends of links 51 by pins 55. As shown in FIGS. 7 and 8, two pairs oflaterally spaced links 51 carry three magnets 53, two of the latterbeing attached to the outer sides of links 51 and the third magnet 53mounted therebetween. Thus, a total of twelve magnets 53 are carried byeach carriage 40 with six mounted on each side thereof. Of course, moreor less than twelve magnets 53 can be carried by each carriage 40,depending on the configuration and size of the specific article beinghandled. Magnets 53 are effective to attach and lift a tray 36 from thestack of trays at pick-up station 37 and hold such tray thereto duringupward vertical movement of carriage 40. Elongated slots 56 are providedin links 51 to permit relative movement between the latter and theplates to which they are mounted to provide tilting movement of barmagnets 53 in at least one plane. Also, some lateral play is providedbetween links 51 and their mounting plates. Thus, bar magnets 53 aregenerally universally suspended from plates 42, 43, 48 and 50 by virtueof the slot 56 and pin 52 arrangement together with the pivotal mountingof links 51 with their respective plates and with bar magnets 53,enabling the latter to be tilted upon engagement with variouslyconfigurated trays. For example, should the left end portion of the lefthand magnet 53 shown in FIG. 7 engage a high surface on tray 36 duringthe lowering of carriage 40 interrupting further downward movement ofthis left end portion, the associated pin 52 will move downwardly inslot 56 allowing the right end portion of magnet 53 to engage a lowersurface on the tray to effect a stronger holding force thereon.Accordingly, the universal suspension of each set of three bar magnets53 from plates 42, 43, 48 and 50 permits the handling of a wide varietyof differently configurated trays without necessitating any adjustmentsor the replacement of parts.

Since the height of the stack of trays at pick-up station 37 varies astrays 36 are singularly removed therefrom, means are provided oncarriage 40 for sensing the uppermost tray 36 in order to effecttermination of the downward movement of carriage 40 and initiate upwardmovement thereof. To this end, an angle member 57 is fixedly secured tocrossplate 45 and has a pair of axially spaced shafts 58 projectinglaterally outwardly therefrom. As best seen in FIG. 7, a sensing plate60 is suspended on shafts 58 by means of at least two slots 61 and 62 inregistry with shafts 58 for receiving the same, such slots beingconfigurated in a manner permitting vertical and tilting movement ofplate 60 in the plane thereof relative to carriage 40. A pair ofretaining collars 63 are mounted on each shaft 58 on opposite sides ofplate 60 for restraining the latter against lateral movement.

Also mounted on carriage 40 by means of an angle member 65 is aproximity limit switch PLS-2 adapted to be actuated by the upper end ofplate 60 when the latter is moved within a range in close proximity toswitch PLS-2, as indicated in phantom in FIG. 8. As shown in FIGS. 7 and8, the lower edge of plate 60 is normally disposed below the lower edgesof bar magnets 53 and will engage the article to be lifted prior toengagement of the bar magnets 53 therewith upon the lowering of carriage40. As a result, downward movement of plate 60 is arrested while switchPLS-2 continues to move downwardly with carriage 40 relative to plate60. When switch PLS-2 moves to within a predetermined distance from theupper edge of plate 60, which is designed to occur at about the time barmagnets 53 engage the uppermost tray 36, switch PLS-2 is actuated toeffect interruption of the downward movement of carriage 40, as willhereinafter be explained in connection with the electrical controlsystem of this invention.

The means for vertically reciprocating carriage 40 in synchronisminclude a pair of drive chains 65, (FIGS. 1 and 3) each movable in anorbital path about a pair of vertically spaced sprockets 66 and 67.Upper sprockets 66 are mounted on a common, horizontally extending shaft68 adjacent the opposite ends thereof, the shaft 68 being suitablyjournalled in axially spaced bearings 70 mounted on the upper end offrame 23. Likewise, the lower sprockets 67 are rigidly secured to acommon, horizontally extending shaft 71 adjacent the opposite endsthereof, the shaft 71 being suitably journalled in axially spacedbearings 72 mounted on the lower end of frame 23. The mounting ofsprockets 66 and 67 on common shafts 68 and 71 assures synchronousmovement of chains 65.

Each carriage 40 is provided with a bracket 73 mounted between bearingblocks 46 and 47 (FIGS. 6 and 7) and projecting outwardly from crossplate 45 for connection to its associated drive chain 65. As shown inFIG. 7, each chain 65 is provided with a pair of connecting rods 75 and76 threaded into the opposite ends of a tapped bore 77 extendingvertically through bracket 73. Rod 75 can be threaded inwardly oroutwardly of bore 77 to adjust the tension on chain 65 and is maintainedin the adjusted condition by means of a nut 78. Rod 75 also is providedwith a slidable collar 80 normally urged against a stop member 81 by ahelical spring 82 mounted about rod 75 between bracket 73 and collar 80.Spring 82 serves as a shock absorber in cushioning the impact resultingfrom sudden starting and stoppage of drive chain 65.

The means for actuating drive chains 65 includes an elongated cylinder83 (FIG. 1) extending vertically and mounted at its opposite ends tovertically spaced angle members 85 rigidly secured to frame 23. Cylinder83 includes a piston 84 (FIG. 10) mounted for reciprocating movementwithin cylinder 83 and having a cable 86 anchored to the opposite sidesof the piston. Cable 86 extends through opposite ends of cylinder 83 andis trained about pulleys 87 and 88 suitably journalled for rotation onstructural members 85. The exposed portion of cable 86 is anchored to achannel shaped bracket 90 as shown at 91 in FIG. 1, the bracket 90 beingrigidly secured to and extending outwardly from a portion of one of thedrive chains 65. Conduits 92 and 93 are tapped into the opposite ends ofcylinder 83 for alternately supplying or evacuating fluid pressure toand from the upper and lower ends of cylinder 83 for lowering andraising carriages 40 through the cable and chain connections. Thus,fluid pressure applied via conduit 91 to the top end of cylinder 83moves the piston therein downwardly effecting an upward movement of theexposed cable 86 to drive chain 65 in a clockwise direction, as viewedin FIG. 1, and lower carriages 40. Of course, fluid pressure appliedthrough conduit 93 to the opposite or lower end of cylinder 83 effectsreverse or upward movement of carriage 40. The two chains 65 andconsequently the two carriages 40 move together in the same directionthrough the common mounting of upper sprockets 66 on shaft 68 and lowersprockets 67 on shaft 71.

The specific articles being handled by the article pick-up and transferassembly 20 of this invention are baking pans or trays 36 having agenerally rectangular shape in plan, as shown in FIG. 2. Each tray 36preferably is formed of a suitable metal covered with a coating of rustand corrosion resistant material and comprises a bottom wall 95 having aplurality of recessed cavities or pockets 96 for receiving doughportions ultimately baked to form buns, rolls and the like. Each tray 36is provided with an inclined, peripheral wall 97 terminating at itsupper end in a horizontally extending peripheral flange or rim 98. Theconfiguration of trays 36 enables them to be conveniently stacked in anefficient nested relation, as shown in FIG. 1. It should be understoodthat the present invention is in no manner limited in use with thespecific baking pans or trays illustrated, nor with baking pans or traysin general, but has utility in any article pick-up and transferoperation.

Means are provided for guiding the fresh stack of trays 36 on conveyorbelts 25 into the proper position at pick-up station 37. Such meansinclude two pairs of vertically extending guide plates 100 and 101having the leading edges thereof flared outwardly, as at 102 and 103 inFIG. 1, to facilitate the passage of the stack of trays 36 therethrough.The lower ends of guide plates 100 and 101 are provided with extensionbars 102' and 103' extending from the guide plate leading edges 102 and103 toward the right end of conveyors 25. Extensions 102' and 103' serveas guide lines facilitating the proper placement of a stack of trays 36on the right end of conveyors 25. Guide plates 100 and 101 are providedwith laterally spaced nuts 104 and 106, respectively, fixedly attachedthereto and threaded on the externally threaded portions 107 and 108 ofa pair of vertically spaced shafts 110 passing through each pair ofguide plates 100 and 101. Shafts 110 are suitably journalled adjacenttheir opposite ends in axially spaced bearings 111 and 112 mounted onframe 23 and fixed against axial movement. The threads on rod portions107 are oppositely oriented from the threads on rod portions 108 so thatrotation of shafts 110 effects axial movement of nuts 104 and 106 andthereby guide plates 100 and 101 toward and away from each other.

All four shafts 110 are connected together for rotation in unison bymeans of a pair of endless drive chains 113 trained about verticallyspaced sprockets 115 and 116 rigidly secured adjacent the one end ofeach pair of upper and lower shafts 110. The lower shafts 110 also areconnected together by an endless chain 117 trained about horizontallyspaced sprockets 118 and 120. One of the upper shafts 110 is providedwith a crank handle 121 for manually rotating such shaft 110 andeffecting rotation of all the other shafts 110 in unison through theendless chain connections. Thus, the spacing between guide plates 100and 101 can be readily adjusted to accommodate pans or trays 36 ofvarious widths and sizes. As shown in FIG. 1, trays 36 extend across thewidths of both conveyor belts 25 and normally project laterally beyondthe opposite outer sides thereof.

The opposed carriages 40 function to remove a single tray 36 from thestack of trays at pick-up station 37 and deliver such tray to transferconveyor 38 which in turn, is effective to transfer tray 36 to aposition above the dual-belt, tray feed conveyor 21 and deposit the tray36 on conveyor 21 when space is made available thereon. Transferconveyor 38 includes a frame 122, of a generally box-like shape in crosssection extending lengthwise between carriages 40 in their upperpositions and having a drive pulley 123 mounted adjacent one end thereofand an idler pulley (not shown) mounted adjacent the other end thereof.An endless belt 125 is guided along the upper and lower sides of frams122 and about drive pulley 123 and the idler pulley for movement in anendless orbital path in a clockwise direction, as viewed in FIG. 1. Themeans for driving belt 125 include a motor M1 operatively connectedthrough a clutch 126 and a gear reduction mechanism 127 to an outputshaft 128 for rotating the same. Shaft 128 is provided with a drivesprocket 130 rigidly secured thereto for driving an endless chain 131,also trained about a sprocket 132. Sprocket 132 is affixed to a shaft133 to which drive pulley 123 is attached. Gear reduction mechanism 127is mounted on a support plate 135 affixed to frame 23. Conveyor belt 125is intermittently operated through the clutch arrangement 126 for apurpose hereinafter explained.

An elongated, permanent bar magnet 136 is mounted in conveyor frame 122along the lower active run of conveyor belt 125 for the purpose ofattracting and holding the metallic trays 36 thereto. As shown in FIG.3, a tray 36 carried along the opposite sides thereof by carriages 40 isremoved therefrom and deposited on the lower or active run of conveyorbelt 125 as carriages 40 move upwardly relative thereto.

As tray 36 approaches the active run of conveyor belt 125 during itsupward movement, it engages a bar 137 pivotally suspended from conveyorframe 122. As shown in FIG. 4, bar 137 is pivotally connected adjacentits opposite ends to the lower ends of a pair of links 138 and 140 as at141 and 142. The upper end of link 138 is pivotally mounted at 143 tothe rear side of conveyor frame 122 and link 140 is pivotally connectedat 145 to the rear side of conveyor frame 122. Link 140 is provided withan extension to form a pivotable bell crank lever 146 normally engagablewith the actuating lever 147 of a limit switch LS-4. The upward movementof bar 137 effected by the engagement of an upwardly moving tray 36therewith causes bell crank lever 146 to swing in a counterclockwisedirection about pivot 145 out of engagement with switch actuating lever147 for a purpose hereinafter explained. Also, as carriages 40 approahtheir upper positions, a cam 148 (FIG. 5) mounted on the side of one ofthe carriages 40 engages a pair of cam followers 150 and 151 connectedto the actuating levers 152 and 153 of a limit switch LS-5 and a pair oflimit switches LS-7A, LS-7B, respectively, for energizing the same for apurpose hereinafter explained in connection with the operation of theapparatus of this invention. A pair of semi-circular grooves 155 areformed in the upper surface of bar 137 to prevent interference thereofwith shafts 110 projecting transversely through conveyor frame 122.

Actuation of conveyor belt 125 in a clockwise direction moves tray 36toward the left as viewed in FIG. 1. As tray 36 moves leftwardly theleading edge thereof engages a lever 156 to actuate limit switch LS-2and effect stoppage of conveyor belt 125, as will hereinafter becomeapparent, positioning tray 36 in overlying relation to the outputstation or tray feed conveyor 21. Conveyor 21 forms a part of anautomated pan or tray feeding system, generally designated 157, whichcontinuously feeds tray 36 in a closely spaced relation to a doughfilling station for ultimate delivery to a baking oven. The efficientand automatic dough filling operation is dependent on a continuoussupply of trays 36. Accordingly, the system 157 is provided with anelectrical control circuit (not shown) to operate the system in aproperly timed relation. In an effort to continuously supply trays 36,means are incorporated in the system's control circuit to ascertain whenspace is available on conveyor 21 for another tray 36. Other meansincluded in the control circuitry of this invention is responsive tothis demand to initiate operation of a stripping means, generallydesignated 160, for stripping a tray 36 from conveyor belt 125 onto theavailable space on tray feed conveyor 21.

In accordance with this invention, stripping means 160 (FIGS. 4 and 5)comprises a support plate 161 overlying conveyor frame 122 in spacedrelation thereto and extending transversely thereof. A pair ofvertically depending angle members 162 and 163 are secured adjacent eachopposite end of support plate 161 along the opposite edges thereof andare welded or otherwise fixedly secured to the opposite sides ofconveyor frame 122. A fluid cylinder 165 is mounted on the centralportion of support plate 161 and is provided with a piston 164 having apiston rod 166 secured thereto. The lower end of piston rod 166 isrigidly secured to a pusher member 167 of generally X shapedconfiguration in plan (FIG. 2) having four legs 168, each of which isprovided with a rod 170 extending downwardly from the distal endthereof. Rods 170 extend through guide bushings 171 mounted in spacedstationary bars 172 secured to the opposite sides of conveyor frame 122.The distal ends of rods 170 are attached to spaced pusher bars 173disposed below stationary bars 172 and movable along the sides ofconveyor frame 122 for engagement with tray 36 carried by the conveyorbelt 125. Conduits 160 and 174 are tapped into the head and rod end ofcylinder 165, respectively, for alternately supplying or evacuating airpressure to and from the head and rod end of cylinder 165 to lower andraise piston rod 166. Lowering of piston rod 166 moves pusher bars 173into engagement with the sides of tray 36 on conveyor belt 125 andstrips such tray therefrom into tray feed conveyor 21.

Referring now to the diagrammatic showing of the fluid pressure system,preferably pneumatic, in FIG. 10, there is shown a main line airpressure supply conduit 175 connected to a suitable source (not shown)and passing through a suitable filter 176. Conduit 175 is divided intotwo pressure supply branch conduits 177 and 178 having suitable pressureregulators 180 and 181 therein. Conduit 177 leads to a two-positiondirectional control valve 182 having a spool valve (not shown) therein,the position of which is controlled by a solenoid SOL No. 5 and asolenoid No. 6. One of the outlets of directional valve 182 is connectedby conduit 93 to the lower end of cylinder 83 below piston 84. Anadjustable flow control valve 183 is provided in conduit 93 forregulating the flow of air pressure therethrough. The other outlet ofdirectional valve 182 is connected to a conduit 185 having a pair ofbranch conduits 186 and 187 leading to conduit 92 connected to the upperend of cylinder 83 above piston 84. An adjustable flow control valve 188is provided in conduit 186 for regulating the flow of air pressuretherthrough. Also provided in conduit 186 is a two-position normallyopen control valve 190 having a spool valve therein shiftable torestrict the flow of air pressure therein, the position of the spoolvalve being controlled by a solenoid SOL No. 7. An on-off control valve191 provided in conduit 187 is operative for by passing air flowdirectly through conduit 187 into and from cylinder 83.

Branch conduit 178 is further branched off into a conduit 170 and aconduit 192, the latter leading to a two-position directional controlvalve 193 having a spool valve therein, the position of which iscontrolled by a pair of solenoids SOL No. 3 and SOL No. 4. Leading fromdirectional control valve 193 are a pair of conduits 195 and 196connected to the upper and lower sides of a cylinder 197 above and belowthe piston therein which is operatively connected to clutch 126.

The branch conduit 179 is connected to a two-position directionalcontrol valve 198 shiftable into opposite directions for admittingand/or exhausting air pressure into either conduit 169 or conduit 174connected to the upper and lower ends, respectively, of strippingcylinder 165 above and below piston 164. Directional valve 198 isshifted into opposite directions by a pair of solenoids SOL No. 1 andSOL No. 2.

The various movements and sequential operation of the article pick-upand transfer assembly 20 described above, which afford continuousautomatic operation of the machine, are the function of a comprehensiveelectrical control system, diagrammatically illustrated in FIG. 11. Allof the electrical switch elements are associated with and activated bythe movable elements of apparatus 20 except for the operation of switchPLS-1 which is effected by the demand for a tray on tray feed conveyor21 of the automated tray feeding system 157. The electrical controlsystem will be described in connection with the operation of apparatus20. In describing the operation of apparatus 20, let it be assumed thata tray 36 is positioned on the right side of the active run of conveyorbelt 125 at the upper end of pick-up station 37 and that there is notray 36 on the left side of conveyor belt 125 beneath the strippingmeans 160. Also, assume that the stack of trays normally located onconveyor belts 25 at pick-up station 37 has been depleted and that thereis a fresh stack of trays 36 on the right side of conveyor belts 25.Under these conditions, limit switch LS-4 is in an open position andswitch LS-2 is in the position shown in FIG. 11. With carriages 40 intheir upper positions, switches LS-5 and LS-7A are closed and switchLS-7B is open.

Referring now to the electrical system, illustrated diagrammatically inFIG. 11, operating current is tapped from the electrical system of theautomated tray feeding system 157, which is connected to a suitablepower source (not shown), the current being supplied through a powerline comprising conductors 202 and 203. In operation, the on-off mainpower switch SW2 is depressed and maintained closed to supply operatingcurrent to conductor 205. An indicator lamp P in lead 206 is illuminatedto indicate that power for the electrical control system is on. Also, acircuit is completed via conductor 205, lead 207 and conductor 203 forenergizing drive motor M1. Also, switch LS-2 is in a positionmaintaining solenoid SOL No. 4 energized via conductor 205, switch LS-2,lead 208, solenoid SOL No. 4 and conductor 203 to maintain directionalvalve 193 in a position supplying air pressure to the top of cylinder197 via conduit 195 to maintain clutch 126 engaged.

Energization of drive motor M1 drives conveyor belt 125 in a clockwisedirection moving tray 36 leftwardly. As tray 36 rides off bar 137, thelatter is lowered by gravity, rotating bellcrank 146 (FIG. 4) aboutpivot 145 into engagement with lever 147 for actuating the same to closethe previously opened limit switch LS-4 in readiness for the carriagelowering operation. Tray 36 continues to move leftwardly on conveyorbelt 125 until it engages lever 156 of limit switch LS-2 to actuate thelatter into its alternate position, completing a circuit via conductor205, switch LS-2, lead 210, solenoid SOL No. 3 and conductor 203 toenergize solenoid SOL No. 3. Energization of solenoid SOL No. 3 shiftsdirectional valve 193 to a position admitting air pressure into the rodend of cylinder 197 via conduit 196 to lift the piston therein andthereby disengage clutch 126 to effect stoppage of conveyor belt 125.

Also, in the absence of trays 36 at the pick-up station 37, proximityswitch PLS-2 in lead 211 is opened and with carriages 40 in their upperpositions, switch LS7-A is closed to energize motor M2 via conductor205, lead 212, normally closed contacts CR3, switch LS7-A, lead 213 andconductor 203. Energization of motor M2 drives conveyor belts 25 inunison in a couunterclockwise direction to move the fresh stack of trays36 on the right side of conveyor belts 25 to the pick-up station 37.Limit swtich LS-7A, which is cammed closed by cam 148 when carriages 40are in their upper positions, provides a fail safe feature in preventingenergization of motor M2 and the advancement of a stack of trays 36 intopick-up station 37 unless carriages 40 are in their upper positions outof the path of movement of the advancing stack of trays 36.

As the lowermost tray 36 on conveyor belts 25 approaches proximityswitch PLS-3, the latter closes to complete a circuit via conductor 205,lead 211, switch PLS-3 and conductor 203 to energize control relay CR3.Energization of control relay CR3 opens the normally closed contacts CR3in lead 212 and interrupts the circuit to motor M2 causing conveyorbelts 25 to stop. Switch PLS-3 remains closed as long as at least onetray 36 is disposed on conveyor belts 25 at pick-up station 37. Motor M2also can be energized by depressing switch JOG in lead 215 to bypass theabove described automatic operation for advancing conveyor belts 25. Afresh stack of trays 36 on a loading support 216 (FIG. 1) adjacentconveyor belts 25 can be placed on the right side of belts 25 inreadiness for the next tray advancing operation.

Energization of control relay CR3 also closes normally open contacts CR3in lead 217 to complete a circuit via conductor 205, lead 217, contactsCR3, switches LS-5 and LS-4, switch SW1 when in its raised position asshown in FIG. 11, solenoid SOL No. 5 and conductor 181 to effectenergization of solenoid SOL No. 5. Energization of SOL No. 5 shiftsdirectional control valve 182 into a position directing fluid pressureinto cylinder 83 (FIG. 1) via conduits 185, 186 and 92 to move piston 84downwardly and effect upward movement of the exposed portion of cable 86and clockwise movement of chain 65 to lower carriages 40. As camfollowers 150 and 151 (FIG. 5) ride off can 148 during the lowering ofcarriages 40, their respective levers 152 and 153 are actuated to opendelay limit switch LS-5 and limit switch LS7-A and close limit switchLS7B. Thus solenoid SOL No. 5 is deenergized and the circuit to motor M2is interrupted to prevent advance of conveyor 25 during the lowering ofcarriages 40. As carriages 40 approach the stack of trays 36 at pick-upstation 37, sensing plate 60 (FIGS. 6 and 7) engages the uppermost tray36 prior to engagement thereof by bar magnets 53, causing the upper edgeof plate 60 to be held stationary relative to the descending proximityswitch PLS-2. At about the time that bar magnets 53 engage the uppermosttray 36, the upper edge of plate 60 will be within the operating rangeof switch PLS-2 to actuate the latter to a closed position completing acircuit for control relay CR2 via conductor 205, lead 218, swtich PLS-2,control relay CR2 and conductor 203 to energize relay CR2. Energizationof control relay CR2 closes normally open contacts CR2 in lead 220 toenergize solenoid SOL No. 6 via conductor 205, lead 220, contacts CR2,switch LS7-B and conductor 203. Also, a time delay relay TD01 in lead221 is energized to open normally closed contacts TD1 in lead 222,deenergizing solenoid SOL No. 7. Also, the energization of time delayrelay TD01 is effective to close normally open contacts TDPU in lead 223after a predetermined time delay to effect reenergization of solenoidSOL No. 7.

Because of the substantially universal suspension of bar magnets 53 inat least one plane, they orient themselves in a manner to make optimumcontact with the upper surface of the uppermost tray 36 when carriages40 are in their lower pick up positions regardless of the specific shapeor configuration of such tray 36 to firmly engage and hold the same byvirtue of the magnetic forces therein.

Energization of solenoid SOL No. 6 shifts directional valve 182 into anopposite position evacuating the upper end of cylinder 83 via conduit 92and directing fluid pressure into the bottom end of cylinder 83 viaconduit 93 to effect downward movement of the exposed portion of cable86 and counterclockwise movement of chain 65 to raise carriages 40 andlift the uppermost tray 36 from the stack of trays at pick-up station37. However, the deenergization of SOL No. 7 is effective to shiftcontrol valve 190 into a position restricting return flow of airpressure from the upper end of cylinder 83 through conduit 92 so thatcarriages 40 initially ascend at a relatively slow rate of speed toprevent disengagement of bar magnets 53 from tray 36 and to facilitatethe gradual and smooth lifting of the uppermost tray 36. After a timedelay, contacts TDPU in lead 223 close to effect energization ofsolenoid SOL No. 7 to shift control valve 190 to a fully open positionto effect unrestricted flow of fluid pressure from the top of cylinder83 and rapid movement of carriages 40 toward their upper positions. Whentime delay relay TD01 times out, contacts TDPU open and contacts TD1 inlead 222 revert to their normally closed positions to maintain solenoidSOL No. 7 energized, thereby permitting unrestricted flow throughcontrol valve 190 during a subsequent carriage lowering operation. Thebar magnets 53 are operative to carry the uppermost tray 36 therewithupon the elevation of carriages 40 and convey such tray 36 to conveyorbelt 125, the tray being attracted to and held on conveyor belt 125 bythe magnetic forces of bar magnet 136 in conveyor frame 122.

As carriages 40 reach the end of their upper strokes, cam 148 (FIG. 5)engages cam follower 150, actuating the associated lever 152 to closetime delay limit switch LS-5 in lead 217 after a predetermined timedelay to prepare the associated circuit for a subsequent carriagelowering cycle. Also, cam 148 engages cam follower 151 actuating theassociated lever 153 to close switch LS7A in lead 212 and to open limitswitch LS7-B in lead 220 to lock out the carriage lifting circuit in theevent plate 60 would tend to continue to move upwardly upon the stoppageof carriages 40 at the end of their upward strokes and inadvertentlyactuate proximity limit switch PLS-2. After plate 60 has stabilizedrelative to carriage 40, and time delay switch LS-5 times out, it closesin readiness for the next carriage lowering cycle.

As tray 36 approaches conveyor belt 125, it engages bar 137 causingbellcrank 146 to pivot in a counterclockwise direction allowing lever147 to swing to actuate limit switch LS-4 in line 217 into an openposition interrupting the circuit for solenoid SOL No. 5 and preventingthe lowering of carriages 40 until tray 36 is conveyed off bar 137.

In the sequence of operations thus far described, a pair of axiallyspaced trays 36 are held on the active run of conveyor bell 125 as shownin solid line and in phantom in FIG. 1. In the meantime, a tray 36 onthe tray feeding conveyor 21 is advancing from beneath stripping means160 to an output station (not shown) and is maintaining proximity switchPLS-1 in line 225 in a closed position, maintaining control relay CR1energized via conductor 202, line 225, switch PLS-1 and conductor 203.Energization of control relay CR1 opens the normally closed contacts CR1in line 226 to prevent energization of solenoid SOL No. 1 and actuationof the stripping means 160 until tray 36 on conveyor 21 advances pastswitch PLS-1 indicating that the tray has advanced sufficiently toprovide space for the reception of another tray 38. As tray 36 onconveyor 21 moves past switch PLS-1, it opens to deenergize controlrelay CR1 and allow contacts CR1 in line 226 to revert to their normallyclosed positions. The closing of contacts CR1 completes a circuit viaconductor 205, switch LS-2, contacts CR1, line 226, solenoid SOL No. 1and conductor 203 to enrgize solenoid SOL No. 1.

Energization of solenoid SOL No. 1 effects shifting of directional valve198 (FIG. 10) for directing air under pressure into cylinder 165 viaconduit 169 to move piston 164 and piston rod 166 downwardly, drivingpusher bars 173 against tray 36 to strip the latter from conveyor belt125 and onto tray feed conveyor 21. Thus, stripping means 160 isresponsive to the demand for a tray 36 at the output station on conveyor21 of system 157. The disengagement of the leading tray 36 fromactuating lever 156 of limit switch LS-2 causes the latter to be shiftedto its alternate position shown in FIG. 11, deenergizing solenoids SOLNo. 1 and SOL No. 3 and energizing solenoids SOL No. 2 and SOL No. 4 vialeads 227 and 208, respectively.

Energization of solenoid SOL No. 2 is effective to shift the directionalvalve 198 to a position directing air pressure into the rod end ofcylinder 165 via conduit 174 for raising piston 164 and piston rod 166and the associated pusher bars 173 upwardly out of the path of asubsequently delivered tray 36.

Energization of solenoid SOL No. 4 effects shifting of directional valve193 into a position directing air pressure into cylinder 197 via conduit192 to effect engagement of clutch 126 to initiate movement of conveyorbelt 125 in a clockwise direction moving tray 36 from station 37 to thetray stripping station beneath stripping means 160. As the advancingtray 36 leaves bar 137, the latter is lowered by gravity, rotatingbellcrank 146 (FIG. 4) about pivot 145 into engagement with lever 147for actuating the latter to close limit switch LS-4 and condition thecarriage lowering circuit for another cycle. Since contacts CR3 are heldclosed by the continued energization of control relay CR3 and limitswitch LS-5 was previously closed upon the ascension of carriages 40,the carriage lowering circuit is completed for lowering carriages 40 ashereinbefore described to remove another tray 36 from the stack of traysat station 37 and deliver the same to conveyor belt 125. When thepreceding advancing tray 36 on conveyor belt 125 reaches the strippingstation, it engages lever 156 to shift limit switch LS-2 to itsalternate position deenergizing solenoids SOL No. 2 and SOL No. 4 andenergizing solenoid SOL No. 3 to disengage clutch 126 and terminatemovement of conveyor belt 125. Meanwhile, the advancing tray 36 onconveyor 21 depresses switch PLS-1 to energize control relay CR1 in lead225 to open normally closed contacts CR1 in line 226 and preventenergization of solenoid SOL No. 1 and the actuation of stripping means160 upon the movement of switch LS-2 to its alternate position.Apparatus 20 is now conditioned for another cycle of operation, asdictated by the demand for another tray 36 on conveyor 21.

Referring now to FIG. 1 and the schematic illustration of FIG. 9, theoperation of the article pick-up and transfer assembly 20 of thisinvention can be summarized as follows:

When the stack of trays normally disposed on the left end of conveyorbelts 25 at pick-up station 37 is depleted, switch PLS-3 is activated toeffect movement of such belts 25 in the direction of arrow A (FIG. 9) tomove a fresh stack of trays 36 into the pick-up station and deactivateswitch PLS-3 to stop conveyor 25. An interlock feature incorporated inthe electric circuitry is effective to prevent lowering of carriages 40when conveyor 25 is operating.

With no trays on conveyor belt 125, carriages 40 are lowered in unisonto bring their associated bar magnets 53 into engagement with theuppermost tray on the stack of trays 36 disposed therebeneath. Throughactuation of proximity switch PLS-2, the electric control circuitry isoperative to effect upward movement of carriages 40 in unison in thedirection of arrow B at an initial slow rate of speed to preventdisengagement of the tray 36 from magnets 53, followed by a rapid upwardmovement thereof to present the tray to conveyor belt 125.

Conveyor belt 125 advances the tray 36 in the direction of arrow C tothe discharge station below the stripping means 160. As the tray 36reaches the discharge station, it engages switch LS-2 to effect stoppageof conveyor belt 125. Also, until the tray 36 on belt 125 is conveyedout of the path of movement of carriages 40, an electrical interlockprecludes lowering of the carriages 40. When the tray 36 is advanced apredetermined distance, carriages 40 are operable to lift another tray36 from the stack of trays at station 37 and present the same toconveyor belt 125.

With two trays supported on conveyor belt 125, apparatus 20 remains at astandstill until demand is made for a tray at the output station onconveyor 21. When the system 157 demands a tray, the stripping means 160becomes operative to strip a tray 36 from conveyor belt 125 in thedirection of arrow D onto conveyor 21. The hereinbefore described cycleof transferring a tray to the discharge station and lifting a singletray from the stack and delivering the same to conveyor belt 125 isrepeated.

As a result of the present invention, an article pick-up and transferassembly is provided for removing a single article from a stack of sucharticles and delivering the single article to a conveyor for transfer toa discharge station whereat the article is expelled upon demand. Theprovision of magnetic pick-up and holding means, which areself-orienting for positive engagement with variously configuratedarticles, assures the removal of a single article only from the stackfor subsequent handling.

A preferred form of this invention having been disclosed in detail, itis to be understood that this has been done by way of illustration only.

I claim:
 1. An article transfer apparatus comprising: an upright frame,means for supporting a stack of articles adjacent the lower end of saidframe, a plurality of upright support rods rigidly secured to saidframe, carriage means vertically slidable on said rods and disposed invertical registry with said article supporting means, means for movingsaid carriage means toward and away from said article supporting means,said carriage means including support plates, a plurality of elongatedrigid members suspended from said support plates, at least one permanentmagnet mounted on the lower end of each of said rigid members, eachmagnet being pivotally mounted at spaced locations thereon to two ofsaid rigid members, means mounting said rigid members on said plates forpivotal movement and bodily vertical displacement relative to saidsupport plates whereby said magnets are self-orienting upon engagementthereof with an irregularly shaped article on said stack, said rigidmember mounting means comprising pins projecting outwardly from saidsupport plates, each of said rigid members having an elongated slot forreceiving a corresponding one of said pins and being suspended thereby,each of said pins being movable along the slot in the corresponding oneof said rigid members to allow said vertical displacement, said verticaldisplacement in conjunction with said spaced pivotal mounting of saidmagnets allowing tilting movement of said magnets substantially in avertical plane, means for sensing the proximity of said magnets relativeto said article upon downward movement of said carriage means, andcontrol means reponsive to said sensing means for interrupting downwardmovement of said carriage means upon engagement of said magnetic meanswith said article and initiating upward movement of said carriage meansto lift said magnets and remove a single article from said stack.
 2. Atransfer apparatus according to claim 1 wherein said carriage meanscomprises a pair of opposed carriages vertically reciprocable in unisonon said upright support rods and each comprising said support plates,said rigid members and said permanent magnets.
 3. An article transferapparatus comprising: an upright frams, means for supporting a stack ofarticles adjacent the lower end of said frame, a plurality of uprightsupport rods rigidly secured to said frame, carriage means verticallyslidable on said rods and disposed in vertical registry with saidarticle supporting means, said carriage means comprising a pair ofopposed carriages vertically reciprocable in unison on said uprightsupport rods, means for moving said carriage means toward and away fromsaid article supporting means, said moving means comprising a pair ofdrive chains each connected to one of said carriages and movable in anorbital path about a pair of sprockets, means connecting said sprocketsfor synchronous rotation, and power means for actuating said drivechains, each of said carriages including support plates, a plurality ofrigid members suspended from said support plates, at least one permanentmagnet mounted on the lower end of each of said rigid members, meansmounting said rigid members on said plates for pivotal movement andbodily vertical displacement relative to said support plates wherebysaid magnets are self-orienting upon engagement thereof with anirregularly shaped article on said stack, means for sensing theproximity of said magnets relative to said article upon downwardmovement of said carriage means, and control means responsive to saidsensing means for interrupting downward movement of said carriage meansupon engagement of said magnetic means with said article and initiatingupward movement of said carriage means to lift said magnets and remove asingle article from said stack.
 4. A transfer apparatus according toclaim 3 wherein said sensing means comprises a sensing plate mounted onsaid carriage means for vertical displacement relative thereto, saidsensing plate having a lower portion engagable with said article priorto the engagement of said magnets therewith.
 5. A transfer apparatusaccording to claim 4 including switch means mounted on said carriagemeans and responsive to movement of said sensing plate relative to saidcarriage means for energizing said control means.
 6. A transferapparatus according to claim 3 including means connecting said drivechains to said carriages, respectively, and shock absorbing meansinterposed between said carriages and said drive chains.
 7. An articletransfer apparatus comprising: an upright frame, means for supporting astack of articles adjacent the lower end of said frame, a plurality ofupright support rods rigidly secured to said frame, carriage meansvertically slidable on said rods and disposed in vertical registry withsaid article supporting means, means for moving said carriage meanstoward and away from said article supporting means, said carriage meansincluding support plates, a plurality of rigid members suspended fromsaid support plates, at least one permanent magnet mounted on the lowerend of each of said rigid members, means mounting said rigid members onsaid plates for pivotal movement relative to said support plates, meansallowing generally bodily vertical displacement of said rigid membersrelative to said support plates whereby said magnets are self-orientingupon engagement thereof with an irregularly shaped article on saidstack, means for sensing the proximity of said magnets relative to saidarticle upon downward movement of said carriage means, said sensingmeans comprising a sensing plate mounted on said carriage means forvertical displacement relative thereto, said sensing plate having alower portion engagable with said article prior to the engagement ofsaid magnets therewith, there being at least one rigid shaft mounted onsaid carriage means and said sensing plate having an elongated slot forreceiving said shaft whereby said sensing plate is verticallydisplaceable relative to said shaft upon engagement of said sensingplate with said article, and control means responsive to said sensingmeans for interrupting downward movement of said carriage means uponengagement of said magnetic means with said article and initiatingupward movement of said carriage means to lift said magnets and remove asingle article from said stack.
 8. A transfer apparatus according toclaim 7 including means on said rigid shaft for restraining lateralmovement of said sensing plate on said rigid shaft.